Mr Ward, the MP for Bradford East, had the party whip restored in September after serving a suspension over a series of clashes with the Lib Dem hierarchy over his views on Israel and its treatment of the Palestinians.

The final straw for leadership was a posting in July last year questioning the future existence of the state of Israel which the party said broke a previous agreement to use "proportionate and precise" language when commenting on the issue.

Mr Ward condemned that ruling as "disproportionate" saying such views were widely shared.

A Labour spokesman said: "At a time when all sides should be working for a ceasefire and a peaceful settlement, it defies belief that a Liberal Democrat MP should tweet something so vile and irresponsible.

"Nick Clegg must act immediately to disassociate his party from this comment."